Field of the Invention
The invention relates to a length-adjustable connecting rod for a reciprocating piston engine, especially an internal combustion engine, comprising at least a first and a second rod part, which two rod parts can be pushed together and/or inside one another in a telescopic manner, wherein the second rod part forms a guide cylinder and the first rod part a piston element which is longitudinally displaceable in the guide cylinder, wherein a high-pressure chamber is spanned between the first and the second rod part, into which at least one first oil duct opens.
The Prior Art
DE 101 51 517 A1 describes a piston and connecting rod assembly of variable length for producing a variable compression ratio in an internal combustion engine, comprising a first part and a second part which are coupled to a length-changing mechanism which is accommodated between the parts. The length-changing mechanism comprises a spring washer shaped in the manner of a truncated cone and an elastomeric mass which rests on a concave surface of the spring washer.
Further connecting rods with a respective hydraulic telescopic mechanism for adjusting the connecting rod length are known from the specifications FR 2 857 408 A1, EP 1 243 773 A1, WO 02/10568 A1, DE 198 35 146 A1, U.S. Pat. No. 4,370,901 A, U.S. Pat. No. 4,195,601 A, U.S. Pat. No. 4,124,002 A and U.S. Pat. No. 2,134,995 A.
By changing the compression, full load can be operated at a lower compression ratio, and partial load and starting at an increased ratio. Consumption is improved in the part-load range, the compression pressure with increased compression ratio is increased during starting, and the peak pressure at reduced ratio is reduced under high load, and knocking is prevented.
It is known to use an eccentric piston pin or an eccentric crankpin fillet of the crankshaft for adjusting the compression ratio. It is further known for changing the compression ratio to lift the entire cylinder block or to lower the entire crankshaft bearing with eccentric bearing thereof in the crankcase.
All these proposals require high constructional and controlling efforts.
It is the object of the invention to avoid these disadvantages and to provide a simple and reliable solution for changing the compression ratio.